just like to add : if the property in UK is owned through inheritance, you can be still be a valid and legal FTB in ireland- but if property in UK or anywhere else is owned through your sources of income, you had effectivley lost the FTB status, also any house bought under an FTB status should not be rented( except under rent-a room scheme) for next 5 years or else there will be a proportinate claw-back of stampduty relief.
it will not be soon revenue start their clampdown or declare an amnsety scheme( given large number of foreign nationals buying here as FTB) to get some dosh ...